Efficiency of different plant cover to control water erosion in central Spain

In Spain, soil quality has been found to change in regions with gradual abandonment of agricultural lands. The response of these lands following abandonment is variable. In some cases the runoff coefficient decreases, but sometimes may increase due to the gradual loss of plant cover under semi-arid conditions with about 500 mm rainfall. The latter situation is now considered a serious environmental concern in Spain. The aim of this work was to study water erosion and runoff in the center of the Iberian Peninsula. The study was undertaken for three consecutive years on experimental USLE-type plots where soil was maintained without vegetation, or covered by natural vegetation or sowed with barley. The water from the runoff was collected in each plot following each rainfall. The influence of the pluviometer, the maximum intensity in 30 minutes, and the kinetic energy of the rain were also measured. The biggest runoff coefficient corresponded to bare soil and there was a gradual increase with time. At the end of the experiment, in some locations, the value of the runoff coefficient reached six times that of the initial value.